AFAIK it doesn't as it's classified as a pet.
SingStar:
"Extremists LOVE to fish to get us annoyed so we break the forum rules."
CRACK68:
"The origin of life wasn't planned either, should all life be declared a bug and wiped out?"
Lionsbane:
"You know me.Ever the realist"
[ QUOTE ]
AFAIK it doesn't as it's classified as a pet.
[/ QUOTE ]
So is Ice Storm 
CoX 50s: <ill/rad> <ice/ice> <fire/kin> <grav/sonic> <ice/storm> <earth/kin> <kin/elec> <cold/psy> <thugs/dark> <fire/dark> <dark/elec> <night widow> <EM/ninj> <mind/icy>
would that be a "yes it does containment damage" or a "no, it doesn't, booo" ?
I miss him in the weeping of the rain;
I want him at the shrinking of the tide;
The old snows melt from every mountain-side,
And last year's leaves are smoke in every lane;
But last year's bitter loving must remain
~Edna St. Vincent Millay
"no, it doesn't, booo" 
CoX 50s: <ill/rad> <ice/ice> <fire/kin> <grav/sonic> <ice/storm> <earth/kin> <kin/elec> <cold/psy> <thugs/dark> <fire/dark> <dark/elec> <night widow> <EM/ninj> <mind/icy>
bah humbug 
Just as well i rolled a defender instead then, only 38 lvls till my nuke, cant wait.
I miss him in the weeping of the rain;
I want him at the shrinking of the tide;
The old snows melt from every mountain-side,
And last year's leaves are smoke in every lane;
But last year's bitter loving must remain
~Edna St. Vincent Millay
It doesn't but is massive anyway, especially with acid arrow, stacked disruption arrows and a mass of impobilised mobs. 
Now that controller epics have been nerfed it is probably the most damaging power available to controllers.
I really should do something about this signature.
Does the damage caused by oil slick when lit benefit from containment? Would seem if it does that the damage would be quite awesome.
I miss him in the weeping of the rain;
I want him at the shrinking of the tide;
The old snows melt from every mountain-side,
And last year's leaves are smoke in every lane;
But last year's bitter loving must remain
~Edna St. Vincent Millay